These settings determine what is obsolete when running the commands and override the CONFIGURE RETENTION POLICY settings. The default value is followed by a number sign (#). The retention policy has the following aspects: As illustrated in Figure5-7, the current time is January 23 and the point of recoverability is January 16.

A backup or copy is obsolete when REPORT OBSOLETE or DELETE OBSOLETE determines, based on the user-defined retention policy, that it is not needed for media recovery. The date and time refer to when RMAN started the backup.

Oracle9i Recovery Manager Reference for BACKUP MAXCORRUPT syntax, and Oracle9i Recovery Manager Reference for COPY MAXCORRUPT syntax. For example, a copy of a datafile that you make with the UNIX dd command is an operating system copy. A differential incremental level 2 backup backs up all blocks that have changed since the most recent incremental backup at level n or less; in this case, the most recent incremental backup at level 2 or less is the level 2 Monday backup, so only the blocks changed since Monday will be backed up. So, RMAN reads the multiplexed data for the first sixteen files and then starts reading the data for data17.f. Hence, each backup set must contain datafiles from at least four disks. In this way, you ensure that all your backups exist on both disk and tape.

For example, you can validate that all database files and archived redo logs can be backed up by issuing a command as follows: You cannot use the MAXCORRUPT or PROXY parameters with the VALIDATE option. each backup piece to 5G use: Channels are released using the RELEASE CHANNEL statement. Specifies the month in the

and day in the Gregorian calendar. The FILESPERSET parameter determines how many datafiles should be included in each backup set, while MAXOPENFILES defines how many datafiles RMAN can read from simultaneously. Table5-4 describes criteria that RMAN uses to determine whether a file is identical to a file that it already backed up. You can specify the CLEAR option for any CONFIGURE command. Oracle9i Real Application Clusters Concepts for information about parallelization in an Oracle Real Application Clusters configuration. The following commands are examples of long-term backups: Oracle9i Recovery Manager Reference for CHANGE syntax.

It does not have to correspond to the actual number of channels configured for the device. "Configuring the Retention Policy for a Recovery Window". Channels are allocated using the ALLOCATE CHANNEL statement. For example, assume that backup set 123 contains three backup pieces, and that BACKUP COPIES 3 was issued so that three copies of each backup piece exist. RMAN provides an efficient way to produce multiple copies of each backup piece in a backup set. Sets a limit to the number of files in the backup set without specifying a maximum size in bytes of the set. The order of precedence is: Note that you can configure the autobackup format even when CONFIGURE CONTROLFILE AUTOBACKUP is set to OFF, but RMAN does not generate autobackups in this case.

type disk maxopenfiles 20 rate 1M maxpiecesize 50M; allocate channel c2 Note that one consequence of this mechanism is that RMAN applies all blocks containing changed data during recovery--even if the change is to an object created with the NOLOGGING option. Combines the database To restrict the size of each backup piece, specify the MAXPIECESIZE option of the CONFIGURE CHANNEL or ALLOCATE CHANNEL commands. A differential incremental level 2 backup backs up all blocks that have changed since the most recent incremental backup at level n or less; in this case, the most recent incremental backup at level 2 or less is the level 0 Sunday backup, so only the blocks changed since Sunday will be backed up. Oracle9i Recovery Manager Reference for ALLOCATE CHANNEL syntax, and Oracle9i Recovery Manager Reference for CONFIGURE syntax.

The configuration acts as a template. A level 0 incremental backup, which is the base for subsequent incremental backups, copies all blocks containing data. You can also simply connect to the target instance in NOCATALOG mode and restore the database. You can either let RMAN determine a unique name for backup pieces or use the FORMAT parameter to specify a name. Run the REPORT OBSOLETE command to determine which backups and copies are currently obsolete according to the retention policy. Multiplexing is affected by the factors described in Table5-1. In this example, after resilvering the mirror (not including other copies of the broken mirror), then you must use a CHANGE UNCATALOG command to update the recovery catalog and indicate that this copy is no longer available. Controls the maximum number of input files that a. Specifies the activation ID

If you specify the DELETE INPUT option, then RMAN backs up exactly one copy of each specified log sequence number and then deletes the copy from disk after backing it up. In this way, you do not cause either disk backups to fail because of space restrictions or tape backups to span multiple volumes. Note that the Tuesday backup of users is obsolete beginning on Thursday. To set a maximum backup set size for a database backup to 10 MB, you issue the following command: Because you did not set FILESPERSET, RMAN calculates the default value for you, comparing 64 to 50/2 and setting FILESPERSET = 25. You can then perform recovery on the copy. You cannot make a backup of a transported tablespace until after it has been specified read/write. In this scenario, the current time is January 30 and the point of recoverability is January 23. By making a more recent backup of tablespace tools on February 21, RMAN allows the media manager to expire the tape containing the superfluous January 3 backup. If RMAN encounters datafile blocks that have not already been identified as corrupt, then it writes them to the backup with a reformatted header indicating that the block has media corruption (assuming that SET MAXCORRUPT is not equal to 0 for this datafile and the number of corruptions does not exceed the limit). As Figure5-2 illustrates, RMAN performs compression on its backups, which means that datafile blocks that have never been used are not backed up. Then, you do not have the problem of keeping tape streaming that sometimes occurs when making incremental backups directly to tape. For Enterprise Edition databases one or more channels can be allocated.

In this case, the channel can read and write in the following order: So in this example, the degree of multiplexing is 3 (the lesser of 6 and 3).

For example, run a backup as follows: If the default device type is DISK, then the preceding command overrides this default and uses the sbt channel configuration. When you recover using SQL*Plus, Oracle applies the blocks and changes during recovery, so it does not matter that the block in the backup was fractured.

The basic algorithm indicates that because you did not specify FILESPERSET or MAXSETSIZE, RMAN should produce a single backup set. Note: A full backup is different from a whole database backup, which is a backup of all datafiles and the current control file. RMAN does not create a separate autobackup piece containing the control file and server parameter file. The most current suitable backup containing the specified file may not be the most recent backup, as can occur in point-in-time recovery. In this case, moving to the beginning of the backup of data17.f may take more time than the restore itself. For example, if you configure PARALLELISM to 3 for the default sbt device and PARALLELISM to 2 for DISK, then RMAN automatically allocates three sbt channels and two DISK channels during the restore. Oracle9i Recovery Manager Reference for the default settings for each CONFIGURE command, and "Showing All RMAN Configuration Settings". The first channel allocated during the backup or copy job creates the autobackup and places it into its own backup set; for post-structural autobackups, the default disk channel makes the backup. If the session detects a fractured block, then it rereads the block until it gets a consistent picture of the data. For example, you may make a database backup on the first day of every year just to keep a record. The FILESPERSET parameter limits the number of files (control files, datafiles, or archived logs) that can go in a backup set. Each incremental level is denoted by an integer, for example, 0, 1, 2, and so forth.

The ORA_SBT_TAPE_1 channel uses the settings for CHANNEL 1 and the ORA_SBT_TAPE_2 channel uses the settings for CHANNEL 2.

Oracle prohibits any attempts to perform operations that result in unusable backup files or corrupt restored datafiles. RMAN only writes image copies to disk. For example, you can specify: Although the recovery window is the best practice for specifying an retention policy, you choose not to specify it because the number of backups that must be kept by the recovery window is not constant and depends on the backup schedule. This example creates 3 copies of the backup of datafile 7: RMAN places the first copy of each backup piece in /tmp, the second in ?/oradata, and the third in the Oracle home. You can either specify that the backup should be kept FOREVER, or specify an end date using the UNTIL clause. If no level 0 backup is available, RMAN makes a new base level 0 backup for this file. During media recovery, RMAN examines the restored files to determine whether it can recover them with an incremental backup. The BACKUP BACKUPSET command uses the default disk channel to copy backup sets from disk to disk. Note that you can always force RMAN to use the basic algorithm by setting DISKRATIO=0.

Thus, if complete recovery is desired, this command switches datafile 3 to the most recent Monday evening copy: Tags can indicate the intended purpose or usage of different classes of backups or file copies. For example, if you back up 70 datafiles and FILESPERSET is 64, then RMAN produces 2 backup sets. of the database. RMAN can do the following: RMAN always only backs up one copy of each distinct log sequence number. within the backup set. When a tag is not unique, then with respect to a given datafile, the tag refers to the most current suitable file.

This functionality is also known as duplexing a backup set. "Restarting a Backup After It Partially Completes" and Oracle9i Recovery Manager Reference for BACKUP syntax.

The completion time for a file in a backup set is the completion time of the entire backup set. You can use the CONFIGURE RETENTION POLICY command to create a persistent and automatic backup retention policy. When LOGS is specified, all logs more recent than the backup are kept as long as the backup is kept. For example, assume that you configure the sbt device and run a backup as follows: Channel names beginning with the ORA_ prefix are reserved by RMAN for its own use. For example, RMAN can read from two datafiles simultaneously, and then combine the blocks from these datafiles into a single backup piece. The server sessions divide the work of backing up the specified files. The following table indicates that some of the copies of the pieces are corrupted or missing, while others are intact. For example, you override automatic channel allocation when you issue a command as follows: RMAN optimizes automatic channel allocation by leaving automatic channels allocated so long as each new command requires exactly the same channel configuration as the previous command.

RMAN makes the backup because no backup of the tablespace exists within the 7-day recovery window.

For example, assume that you archive logs 121 to 124 to two archiving destinations: /arch1 and /arch2. Note that if backup optimization is enabled when you issue the command to back up a backup set, and the identical backup set has already been backed up to the same device type, then RMAN skips the backup of that backup set. If the database is in ARCHIVELOG mode, then the target can be open or closed: you do not need to close the database cleanly. A backup set, which is a logical object, contains one or more physical backup pieces. An incremental backup reads the entire file and then backs up only those data blocks that have changed since a previous backup. In this case, RMAN only skips backups of offline or read-only datafiles when there are r + 1 backups of the files, where r is set in CONFIGURE RETENTION POLICY TO REDUNDANCY r. Assume that you enable backup optimization and set the following retention policy: So, RMAN only skips backups when three identical files are already backed up. RMAN uses this data to resynchronize the recovery catalog. Choose a backup scheme according to an acceptable MTTR (mean time to recover).

Note that in this case the long-term backup must be consistent. Backup pieces are operating system files that contain the backed up datafiles, control files, or archived redo logs. Incremental backups at levels greater than zero only copy blocks that were modified. To see the default configuration settings, run the SHOW ALL command before entering any configurations of your own. COPIES setting, so RMAN sets n=2. You can override the default device for backups and copies by specifying a different device on the command using the channel.

You can specify a different CONNECT string for each channel to connect to different instances of the target database, which is useful in an Oracle Real Application Clusters configuration for distributing work across nodes.

For example, if RMAN tries to back up a datafile but the datafile is not on disk, then RMAN terminates the backup. Run CROSSCHECK periodically to synchronize the repository with the media manager.

The automatic backup of the control file occurs in addition to any backup of the current control file that has been performed during these commands. Each backupSpec clause produces at least one backup set.

For example, if datafile copies are created each Monday evening and are always tagged mondaypmcopy, then the tag refers to the most recent copy (assuming that no SET UNTIL command is issued before restore or recovery). A full backup includes all used data blocks in the datafiles.

One effective strategy is to make incremental backups to disk and then run BACKUP BACKUPSET to copy the backups to a media manager. On Sunday, you delete all obsolete backups, which removes the Tuesday backup of users. 79693180 bytes, Database Buffers The advanced algorithm also factors in DISKRATIO, which here defaults to 5 (the same value as FILESPERSET).

You only need to specify: RMAN executes commands sequentially; that is, it completes the current command before starting the next one. Now, assume that FILESPERSET is 6 and MAXOPENFILES is 3.

by default, which

One danger in making online backups is the possibility of inconsistent data within a block. Hardware multiplexing occurs when the media manager writes multiple RMAN backups to a single sequential device (such as a tape drive). For example, BACKUP COPIES 1 DATAFILE 7 TAG foo creates one backup set with tag foo.

The following query displays the number of blocks written to a backup set for each datafile with at least 50% of its blocks backed up: Compare the number of blocks in differential or cumulative backups to a base level 0 backup. This situation occurs because restoring the January 28 backup does not enable you to recover to the earliest time in the window, January 23.

Hence, the advanced algorithm dictates that each of the 10 backup sets must contain datafiles from at least 5 of the 6 disks.

Whether you allocate channels manually or automatically, you can use channel control commands and options to do the following: On some platforms, the channel allocation and channel control commands specify the name or type of an I/O device to use. database, padded on the right with. A companion command, DELETE OBSOLETE, deletes the files rendered obsolete by the retention policy. The new catalog will be populated with backup information from the restored control file.

Use the V$PROXY_DATAFILE view to obtain the proxy copy information. If you specify neither parameter, then DISKRATIO defaults to 4.

If you specify the DELETE ALL INPUT option, then RMAN backs up exactly one copy of each specified log sequence number and then deletes the copies that match the specified criteria.

Backup optimization is enabled when the following conditions are true: For example, assume that you run these commands: If none of these files has changed since the last backup, then RMAN does not back up the files again, nor signal an error if it skips all files specified in the command.